The crop tool allows you to crop images from within Perfectly Clear QuickDesk.

Click 'Start Cropping' to switch into crop mode, then use the Aspect Ratio selection to define the height / width of the crop frame.  Select 'Free Resize' to set an arbitrarily sized crop.

You can rotate the image in 90° increments using the first button below the aspect ratio selection. The next two button allow you to flip the image horizontally or vertically.

You can switch between four different composition guides while cropping with the buttons at the bottom of the crop tool